Blender - HDR makes objects too bright
You can change the brightness of the environment texture in the world section by modifiying the Strength value for the HDR. 



Read:

How can I create a silhouette using HDR in cycles?

and 

Increase brightness of HDR to light the scene, but keeping the background at a lower exposure

and 

How do I adjust for overexposure using physically based lighting?

and

How to scale properly HDRI image, to be used in ASC-CDL HDR render?